The invention relates to an electronic sewing machine and more particularly relates to a pattern elongation system of the sewing machine to produce a pattern of stitches enlarged or reduced in the fabric feeding direction with a constant feeding pitch such as the satin stitches. The sewing machine has an electronic memory storing stitch control data which are optionally read out to control the needle positions, so as to adjust the configuration of a pattern of stitches in a manner as mentioned.
According to the pattern elongation device of the sewing machine, the transmission mechanism from a pattern cam to the stitch forming instrumentalities is mechanically adjusted, and therefore the device is in general mechanically complex to produce various elongated patterns symmetrical or asymmetrical, and has been actually difficult to be reduced into practice. In fact, no pattern elongation device or system has been proposed in an electronic sewing machine having a memory storing the stitch control data.